Flank Contact Silent Chains

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EP-SC3, EP-SC4, and EP-SC5 inverted tooth silent chains for high-speed, low-noise power transmission in automotive camshaft drives, industrial gearboxes, printing machinery, and textile equipment. Pitch 9.525 mm to 15.875 mm. Chain widths 10.5 mm to 78.0 mm. Middle guide and side guide configurations. Up to 137.6 kN average tensile strength.

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SC3 / SC4 / SC5

GB Standard Series

9.525 to 15.875mm

Pitch Range

10.5 to 78.0mm

Chain Width Range

Low Noise

High Speed Operation

Flank Contact Silent Chain - Product Overview

Ever-Power flank contact silent chains - also known as inverted tooth chains - are a fundamentally different chain design from conventional roller chains. Where a roller chain engages the sprocket through rollers sitting in the tooth spaces and being lifted in and out of engagement as the chain wraps around the sprocket, a silent chain engages through the flanks of toothed link plates that mesh with the sprocket teeth in a manner resembling gear tooth engagement. This flank contact principle is what gives the silent chain its defining characteristic: smooth, near-silent operation at high speed without the chordal action noise that makes roller chains increasingly loud as chain speed rises above about 6 m/s.

The EP-SC3, EP-SC4, and EP-SC5 series follow the GB (Chinese national standard) designation for flank contact silent chains. EP-SC3 has a pitch of 9.525 mm - the smallest in the range - and is used in compact high-speed drives where the sprocket diameter must be small. EP-SC4 at 12.700 mm pitch is the most widely used silent chain in industrial and automotive applications, balancing load capacity, speed capability, and sprocket size. EP-SC5 at 15.875 mm pitch is the heaviest-duty series, used where the power to be transmitted is too high for a single EP-SC4 chain of practical width, or where the slower speed of the drive allows the larger pitch.

Each pitch series is available in a wide range of chain widths, expressed in the specification table as the minimum inner width b (mm). The chain width determines the number of link plates across the chain width (column n in the table) and directly governs the tensile strength and power capacity of the chain. A wider chain - more plates - carries proportionally more load. The chain width is specified in 3 mm increments for EP-SC3, and varies by series for EP-SC4 and EP-SC5.

Two guide configurations are available. The Middle Guide (Middle Guide) uses a guide plate at the centre of the chain width, running in a groove machined into the centre of the sprocket. This is the standard configuration for most industrial gearbox and automotive timing drive applications. The Side Guide (Side Guide) uses guide plates at both outer edges of the chain, running on the outer faces of the sprocket. Side guide is used where the sprocket cannot have a centre groove - for example, in applications sharing a sprocket with another drive element, or where the sprocket is too narrow to machine a centre groove.

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Dimension key: P = Pitch (mm)  |  b min = Chain width / inner width (mm)  |  d2 max = Pin diameter (mm)  |  L max = Pin length (mm)  |  Lc max = Pin length for connecting link (mm)  |  h1 = Distance from hole centre to tooth tip (mm)  |  h2 max = Plate depth (mm)  |  T max = Plate thickness (mm)  |  Guide type: Middle (Inside) = Middle guide / Side (Outside) = Side guide  |  n = Number of plates  |  Q min = Min. tensile strength kN/lbf  |  Q0 = Average tensile strength kN  |  q = Weight kg/m

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EP-SC3 Silent Chain Specifications (Pitch 9.525 mm)

Pin diameter d2 max 3.95 mm. Plate depth h2 max 10.0 mm. Plate thickness T max 1.5 mm. h1 (hole centre to tooth tip) 5.3 mm. Guide: Side (Outside) = Side guide; Middle (Inside) = Middle guide.

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EP Model b min (mm) L max (mm) Lc max (mm) Guide Type Plates (n) Q min (kN/lbf) Q0 (kN) q (kg/m)
EP-SC3-10.5 10.5 15.8 17.5 Side 7 8.0/1798 8.9 0.48
EP-SC3-13.5 13.5 18.5 20.0 Side 9 10.0/2272 11.2 0.60
EP-SC3-16.5 16.5 21.5 23.0 Side 11 12.5/2840 14.0 0.73
EP-SC3-19.5 19.5 24.5 26.0 Side 13 15.0/3409 16.8 0.85
EP-SC3-22.5 22.5 27.5 29.0 Side 15 17.5/3997 19.6 1.00
EP-SC3-28.5 28.5 33.5 35.0 Middle 19 22.5/5114 25.2 1.26
EP-SC3-34.5 34.5 39.5 41.5 Middle 23 27.5/6182 30.8 1.60
EP-SC3-37.5 37.5 42.5 44.0 Middle 25 30.0/6744 33.6 1.73
EP-SC3-40.5 40.5 45.5 47.5 Middle 27 32.5/7306 36.4 1.86
EP-SC3-43.5 43.5 48.5 50.2 Middle 29 35.0/7868 39.2 1.99
EP-SC3-46.5 46.5 51.5 53.0 Middle 31 37.0/8318 41.4 2.12

EP-SC4 Silent Chain Specifications (Pitch 12.700 mm)

Pin diameter d2 max 5.08 mm. Plate depth h2 max 13.4 mm. Plate thickness T max 1.5 mm. h1 (hole centre to tooth tip) 7.0 mm.

EP Model b min (mm) L max (mm) Lc max (mm) Guide Type Plates (n) Q min (kN/lbf) Q0 (kN) q (kg/m)
EP-SC4-19.5 19.5 24.5 26.0 Side 13 23.4/5318 26.2 1.15
EP-SC4-22.5 22.5 27.5 29.0 Side 15 27.4/6227 30.6 1.33
EP-SC4-25.5 25.5 30.5 32.0 Side 17 31.3/7114 35.0 1.50
EP-SC4-28.5 28.5 33.5 35.0 Middle 19 35.2/8000 39.4 1.68
EP-SC4-34.5 34.5 39.5 41.0 Middle 23 43.0/9772 48.1 2.04
EP-SC4-40.5 40.5 45.5 47.0 Middle 27 50.8/11364 56.8 2.39
EP-SC4-46.5 46.5 51.5 53.0 Middle 31 58.6/13318 65.6 2.74
EP-SC4-52.5 52.5 57.5 59.0 Middle 35 66.4/15091 74.3 3.10
EP-SC4-61.5 61.5 67.8 69.5 Middle 41 78.2/17579 86.8 3.68

EP-SC5 Silent Chain Specifications (Pitch 15.875 mm)

Pin diameter d2 max 5.92 mm. Plate depth h2 max 16.7 mm. Plate thickness T max 2.0 mm. h1 (hole centre to tooth tip) 8.7 mm. All widths Middle guide (Middle Guide) unless noted.

EP Model b min (mm) L max (mm) Lc max (mm) Guide Type Plates (n) Q min (kN/lbf) Q0 (kN) q (kg/m)
EP-SC5-22.0 22.0 29.0 30.2 Middle 11 32.6/7328 36.1 1.62
EP-SC5-26.0 26.0 33.0 34.2 Middle 13 39.0/8767 43.2 1.92
EP-SC5-30.0 30.0 37.0 38.2 Middle 15 45.6/10364 50.6 2.21
EP-SC5-34.0 34.0 41.0 42.2 Middle 17 52.1/11712 57.8 2.51
EP-SC5-38.0 38.0 45.0 46.2 Middle 19 58.6/13318 65.0 2.80
EP-SC5-42.0 42.0 49.0 50.3 Middle 21 65.1/14634 72.2 3.10
EP-SC5-46.0 46.0 53.0 54.2 Middle 23 71.7/16295 79.5 3.39
EP-SC5-50.0 50.0 57.0 58.4 Middle 25 75.0/16860 83.2 3.69
EP-SC5-54.0 54.0 61.0 62.4 Middle 27 84.7/19250 94.0 3.99
EP-SC5-62.0 62.0 69.0 70.4 Middle 31 97.7/22204 108.4 4.58
EP-SC5-66.0 66.0 73.0 74.4 Middle 33 100.0/22480 111.0 4.88
EP-SC5-70.0 70.0 77.0 78.4 Middle 35 111.0/24953 123.2 5.18
EP-SC5-78.0 78.0 85.0 86.4 Middle 39 124.0/27875 137.6 5.77

Silent Chain - Key Technical Features

Flank Contact Engagement - No Chordal Action

The inverted tooth plate flanks engage the sprocket tooth flanks in a sliding contact action that eliminates the cyclic speed variation (chordal action) present in all roller chain drives. In a roller chain, the chain speed varies sinusoidally as each roller enters and leaves the sprocket tooth space; this variation increases with chain speed and is the primary source of roller chain noise and vibration at high speed. Silent chains are free of this effect, giving genuinely smooth velocity ratio and near-silent operation even at speeds above 20 m/s.

Width-Based Load Scaling

Silent chain load capacity scales linearly with chain width because load is shared across all plates in the width. For a given pitch, selecting a wider chain increases the tensile strength and power capacity without any change to the pitch or sprocket. This makes silent chains particularly flexible for power upgrading - moving from EP-SC4-28.5 (35.2 kN) to EP-SC4-61.5 (78.2 kN) requires only a wider chain and sprocket at the same 12.7 mm pitch.

Middle Guide and Side Guide Configurations

Middle guide (Middle Guide) chains use a central guide plate running in a groove in the sprocket face, keeping the chain tracking centrally without lateral drift. This is the standard configuration for most enclosed gearbox and automotive timing drives. Side guide (Side Guide) chains use guide plates at both outer edges, suitable where a centre groove cannot be provided. The narrower widths in EP-SC3 and EP-SC4 use side guide; wider chains with more plates across the width use middle guide.

High Speed Capability

EP-SC3 silent chains at 9.525 mm pitch can operate reliably at chain speeds above 20 m/s with correct lubrication, far exceeding the practical limit of roller chains at the same pitch. EP-SC4 at 12.700 mm pitch is rated up to approximately 15 m/s for continuous operation, and EP-SC5 at 15.875 mm pitch is suitable for speeds up to 10 m/s. These characteristics make silent chains the preferred choice for high-speed camshaft drives, generator drives, and any application where noise is a primary constraint.

Oil Bath Lubrication

Silent chains require continuous oil lubrication, typically from an oil bath in which the chain partially immerses as it travels around the lower sprocket, or from an oil spray directed at the chain-sprocket engagement zone. Unlike roller chains which can tolerate intermittent oil application in some low-speed situations, silent chains always require a continuous oil film at the flank contact zone. The oil also provides the heat removal function, carrying away the frictional heat generated at the flank contact interface during high-speed operation.

Precision Sprocket Tooth Form

Silent chain sprockets use a 30-degree included angle straight-sided tooth profile (as shown in the dimension drawing at the top of the specification table) rather than the involute tooth form of roller chain sprockets. The tooth profile must be precisely machined to the specified 30-degree angle and the h1 dimension (hole centre to tooth tip) for correct chain engagement. Sprockets with worn, mis-machined, or incorrect tooth profiles will cause rapid chain wear and noise generation. EP can supply matched sprockets with verified 30-degree tooth profiles for all SC3, SC4, and SC5 chain sizes.

Applications

Automotive Camshaft and Timing Drives

EP-SC3 and EP-SC4 chains are widely used in automotive engine camshaft timing drives, oil pump drives, and balance shaft drives. The silent operation eliminates the timing chain rattle that afflicts roller chain timing drives at cold start, where oil viscosity delays lubrication reaching the chain. The precise velocity ratio of silent chain engagement also provides more accurate valve timing than roller chain alternatives, contributing to lower emissions and improved fuel economy at the engine development level.

Industrial Gearboxes and Machine Tools

EP-SC4 and EP-SC5 chains are specified for enclosed industrial gearbox drives, machine tool spindle drives, and precision manufacturing equipment where noise is a quality and regulatory consideration. Textile machinery, printing machinery, and packaging equipment all use silent chains in primary drives where roller chain noise would be both unacceptable to operators and potentially masking mechanical fault noise that maintenance teams need to detect. EP-SC4 in widths 28.5 mm to 61.5 mm covers the majority of gearbox and machine tool drive requirements.

Generator and Compressor Drives

Generator drives and compressor drives using EP-SC4 and EP-SC5 silent chains benefit from the smooth velocity ratio, which reduces torsional vibration exciting the driven equipment. In generator applications, velocity ratio variation from a roller chain drive modulates the output voltage and frequency slightly; silent chain eliminates this modulation. In reciprocating compressor drives, silent chain reduces the amplitude of torsional excitation in the drive train, extending bearing and shaft seal life compared to roller chain alternatives at the same power level.

Ever-Power silent chain pitch and tooth profile measurement quality inspection

Matching Sprockets and Other Chain Types

Ever-Power silent chain sprockets 30-degree tooth profile for SC3 SC4 SC5 chains

Matched sprockets with precision 30-degree tooth profiles for all EP-SC3, EP-SC4, and EP-SC5 chain widths are available through our partner site sprocket-chain.net. Middle guide groove sprockets and side guide rim sprockets both available.

View Matching Sprockets →

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Frequently Asked Questions

Why is a silent chain quieter than a roller chain at the same speed?
A roller chain engages the sprocket by with each roller falling into a tooth space as the chain wraps around the sprocket. As the roller settles into the tooth space, there is an impact - the roller hitting the tooth - which generates noise proportional to the impact velocity and chain speed. At high speed, this impact noise becomes dominant. A silent chain engages differently: the inverted tooth plate flanks slide along the sprocket tooth flanks in a meshing action, with the engagement velocity much lower than the equivalent roller impact velocity. The 30-degree tooth angle also distributes the engagement contact over a short sliding distance rather than a single impact point, further reducing the noise impulse per tooth engagement.
What is the difference between middle guide (Middle Guide) and side guide (Side Guide)?
Middle guide chains (Middle Guide) have one or more guide plates positioned at the centre of the chain width. These guide plates have a flat face that runs in a groove machined into the centre of the sprocket face, keeping the chain aligned laterally as it travels around the sprocket. The groove on the sprocket face is the key identifier - look for a central groove in the sprocket. Side guide chains (Side Guide) have guide plates at both outer edges of the chain, and these guide plates run on raised rim faces on the outer edges of the sprocket rather than in a groove. The specification table uses Side (Outside) to indicate side guide and Middle (Inside) to indicate middle guide. When ordering a replacement chain, verify which guide type the existing sprockets are machined for before specifying the chain.
How do I specify the correct chain width for my power requirement?
Choose the pitch first (SC3, SC4, or SC5) based on the sprocket size available and the chain speed. Then calculate the chain tension from the transmitted power: tension (kN) = power (kW) divided by chain speed (m/s). Apply a service factor for the drive type (1.0 for smooth, 1.3 for moderate shock, 1.5 for heavy shock) to get the design tension. Divide the design tension by 5 (minimum safety factor for silent chains) to get the required minimum tensile strength. Find the first row in the specification table for your chosen pitch series where Q min (kN) exceeds this required value, and that is the minimum chain width for your application. Choose the next size up if the calculated width is at the limit of the Q min column.
What lubrication is required for silent chains?
Silent chains require continuous oil lubrication at all times during operation. The preferred method is oil bath lubrication, where the chain partially submerges in an oil sump as it passes around the lower sprocket - the oil is carried into the flank contact zone by the chain and sprocket rotation. The oil level should be maintained at the centre of the lower sprocket shaft. For high-speed applications (above 10 m/s), oil spray directed at the chain-sprocket engagement point is preferred, as the chain speed throws bath oil away from the contact zone before it can enter. Use ISO VG 100 to VG 220 mineral oil depending on operating temperature. Change the oil at the manufacturer-recommended intervals - contaminated oil with metallic particles from chain wear will accelerate tooth and plate wear significantly.
What are the signs that a silent chain needs replacement?
The primary wear indicator for silent chains is elongation, measured as the percentage increase in pitch over a 10-link section compared to nominal. Replace when elongation reaches 1.5% for precision drives (automotive timing, machine tool) or 2.0% for general industrial drives. Visual signs that indicate replacement is needed: visible wear on the plate flank contact surfaces (polished or grooved areas on the 30-degree face of the link plates); looseness or play at pin joints beyond what is typical for a new chain; the chain has ridden visibly higher on the sprocket teeth than when new (indicating the tooth tip is no longer contacting the bottom of the plate window); or the chain noise has returned despite correct lubrication, indicating the flank contact geometry has worn away from the original profile.
Can silent chains be cut to length and joined with a connecting link?
Yes. Silent chains are cut to the required number of pitches and joined with a connecting pin. The Lc max dimension in the specification table is the pin length for the connecting link position, which is slightly longer than the L max running pin length to accommodate the cotter pin or spring clip retention at the chain ends. When cutting a silent chain to length, the cut must be at a pin position, not through a plate. The number of pitches in the circuit must be determined from the centre distance between sprockets and the sprocket tooth count, using the standard chain length formula. For automotive timing chains, the length is fixed by the engine design and should be ordered to the exact link count specified in the engine service manual rather than calculated.

What Our Customers Say

★★★★★

"We replaced roller chains on our high-speed printing press intermediate drives with EP-SC4-34.5 silent chains. The noise level in the press room fell by approximately 6 dB immediately after installation. Operators noticed the difference within the first shift. The EP chains have been running for 14 months at 12 m/s chain speed with no significant elongation and no lubrication issues."

K.H., Maintenance Engineer
Germany - Commercial Printing Plant

★★★★★

"We specified EP-SC3 chains for our compact generator sets. The roller chain drive on the original design was generating vibration that showed up in the output voltage waveform. Switching to EP-SC3-22.5 silent chains eliminated the velocity ratio variation and the voltage ripple dropped below the instrument detection threshold. A straightforward solution to what had been a difficult problem."

L.W., Chief Engineer
Taiwan - Generator Set Manufacturer

★★★★★

"EP-SC5-54.0 chains for our industrial gearbox output drives at 8 m/s. We ordered six chains with 10-pitch measurement confirmation on delivery. All six chains measured within 0.06 mm of nominal over the 10-pitch test length. Installation was straightforward and the chains have been running for 22 months without any adjustment. Very satisfied with the dimensional quality."

F.R., Procurement Manager
Italy - Industrial Gearbox Manufacturer

★★★★★

"We use EP-SC4 chains in our textile machinery main drives. The key requirement is consistent pitch - any variation shows up as fabric defect in the weave. EP chains have never caused a pitch-related fabric fault in three years of production use. The middle guide tracking is also very stable; we have not needed to adjust sprocket alignment after the initial installation on any of the 24 looms fitted."

C.Y., Technical Manager
South Korea - Textile Machinery Manufacturer

Request a Quotation for EP Silent Chains

Provide the EP chain series (SC3, SC4, or SC5), the chain width (b min, mm from the specification table), guide type (middle or side), the number of pitches or metres required, and whether a connecting pin is needed. For automotive timing applications, also provide the engine manufacturer and model. Our team responds within one business day.

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